.cenav{
    height: 726px;
    overflow: hidden;
   div{
    position: relative;
    top:0px;
    transition: 1s;
   }
    img{
        height: (710/3)px;
        width: 100%;
    }
    .btn{
        position: absolute;
       
        height: 30px;
        background: pink;
        display: block;
        width: 100%;
        text-align: center;
        line-height: 30px;
    }
    .top{
        top:0px;
    }
    .bottom{
        bottom: 0px;
    }
}